Optical detector devices, which generate an electrical output signal upon exposure to a beam of light are known in the art. For example, common photodiodes are used to detect light and to generate an electrical current in dependence of the intensity of the incoming light, incident to its light-accepting surface.
Lately, colour-controllable LED lighting units are gaining significance in the market, for example for lighting and healthcare applications. A problem arises when a precise colour-control of the light is needed, for example within the above-mentioned applications. It is thus desirable to be able to detect not only the intensity, but further the spectral composition of the generated light. Especially in lighting environments with heterogeneous light sources, colour-stabilisation or colour-control of the LED lighting units is important. Thus, accurate optical detector devices are necessary, which are able to obtain information on the spectral composition of a beam of light.
Document U.S. Pat. No. 5,965,873 discloses an optical spectrometer, which allows to detect an input beam of light and to generate a corresponding electrical output signal. The spectrometer comprises a silicon substrate with integrally formed, stacked layers of photodiodes, each having an independent spectral response to the incoming light. A signal processing circuit weights each signal of the photodiodes to obtain an electrical output signal in response to the overall spectral composition according to a given sensitivity.
However, although such devices allow to obtain information over a given wavelength range, it is not easily possible to adapt the device to a desired wavelength range without major modifications to the set-up of the device. For the above applications, it would be desirable for the user to define the spectral response of the device, according to the specific application. It is therefore an object to provide an optical detector, which may be adapted to a desired spectral response in a very flexible way and which may be manufactured cost-efficiently.